12713020-002-2 Revision D – April 2004
SSU-2000 User’s Guide 403
Antennas
Installing Antennas
Cutting Antenna Cables
Selecting the Proper Gain Antenna
When installing the GPS radio receiver, it is important to select the proper gain
antenna and coaxial cable that accounts for the insertion loss between the antenna
and the radio receiver to avoid under-driving or over-driving the radio receiver
antenna input. The gain required at 1575 MHz for a GPS radio receiver input is the
manufacturer’s specification for the radio receiver to acquire satellites, with some
level of signal degradation allowed.
L1 Antenna gains are usually specified as the minimum effective gain. Such
antenna gains can have 4.5-10 dB more signal strength at different satellite
azimuths and elevations, depending on their reception pattern. The GPS engine
requires a signal level at the antenna connector input of the chassis to be between
13.8 dB and 36.8 dB. This tolerance allows for the signal loss of the internal coaxial
cable and connectors. The optimal signal level at the radio receiver input is 25.3 dB.
All antenna kits include the GPS L1 antenna, mounting pipe, floor flange, transient
eliminator, pre-assembled coaxial cable (for antenna to transient eliminator), roll of
3M 2150 weatherproof tape, and a right angle adapter. All chassis, antennas,
transient eliminators, and in-line amplifiers have N-type connectors.
All chassis, antennas, transient eliminators, and in-line amplifiers have N-type
connectors.
Recommendation:
Symmetricom recommends that you coil excess
cable to avoid gain mismatch between the GPS antenna and the
radio receiver. Coiling the excess cable also allows you to use the
factory-installed crimped connector.
Recommendation:
Symmetricom
does not
recommend cutting the
antenna cables provided in the GPS Antenna Kits. If you must cut the
cables, please ensure that the following requirements are met.
Be aware of these cable and connector requirements before cutting
antenna cables:
Cable Requirements
– The total cable length from the radio receiver
to the antenna must not be shorter than the minimum cable lengths
indicated in the GPS Antenna Kits
Connector Requirements
– The cables provided with the GPS
Antenna Kit have factory installed crimped connectors. If you cut
these cables, you must supply and add a connector. Symmetricom
recommends that you use only crimp-style N-type connectors in the
Crimper Kit for this application (see
Содержание SDU-2000
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Страница 142: ...Clock Module Reference Data Communications Module 142 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 172: ...Input Module Reference Data Input Adapter Panels 172 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 222: ...Output Module Reference Data Output Adapter Panels 222 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 390: ...SNMP Protocol 390 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 420: ...I O Connector Grounding 420 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...
Страница 434: ...User Changes to Factory Defaults 434 SSU 2000 User s Guide 12713020 002 2 Revision D April 2004 ...